1. Field of the Invention
The present invention relates to a machining error correction apparatus that automatically corrects machining errors in a plurality of grinding devices each of which cylindrically grinds the circumferential surface of the semiconductor ingot and which also grinds part of the circumferential surface along the direction of the axis to form an orientation flat or notch and that automatically corrects machining errors in a plurality of cutting devices each of which cuts the semiconductor ingot at alight angle to its axis.
2. Description of the Prior Art
A semiconductor ingot that has been formed as a single crystal is cut into blocks of a set length by cutting devices and is then cylindrically ground by grinding devices until its outer circumferential surface attains a set diameter. The grinding device also grinds a part of the outer circumferential surface in the direction of the axis to form an orientation flat of a set width or a notch of a set depth.
In the prior art, for each one of the plurality of cutting devices, one block is taken periodically to measure the machining error in length and then the operator performs correction for that particular cutting device. Likewise, for each of the grinding devices one block is periodically taken to measure the machining error in diameter and in width of orientation flat or in depth of notch and the operator performs correction on the relevant grinding device.
However, it is time consuming to perform such corrections as described above for each of the cutting devices and grinding devices. Also, even when the machining error is obtained for a single block, it is very possible that incidental machining errors will occur and, therefore, such corrections will not be accurate. Also, if a correction apparatus is to be provided for each cutting device and each grinding device, the entire structure of the system becomes complicated and corrections cannot be made efficiently.